Atrial septal defect accounts for about 20% of the total incidence of congenital heart disease, atrial septal defect in infancy is generally asymptomatic, and the disease is usually detected by murmurs heard during physical examination. Shortness of breath and bronchitis due to pulmonary vascular congestion. When crying, pneumonia, or heart failure occurs, the right atrial pressure may exceed the left atrium, and a temporary right-to-left shunt may occur, resulting in cyanosis. During physical examination, a systolic grade II-III blowing murmur can be heard mainly between the 2nd and 3rd ribs at the left border of the sternum.